The present invention generally relates to a hybrid vehicle drive device having an engine and a motor as a driving source. More particularly, the present invention relates to a vehicle drive device having an engine power cut-off clutch in a hydraulic transmission having a lock-up clutch.
A drive device for transmitting rotation generated by a driving source to a speed change mechanism through a hydraulic transmission having a lock-up clutch has been widely used as a drive device that is mounted on a hybrid vehicle. This type of drive device has an engine power cut-off clutch for transmitting or cutting off a driving force of an engine to and from a hydraulic transmission. The lock-up clutch is an element for transmitting a driving force generated by a power source to a speed change mechanism without using a fluid, and when the vehicle speed reaches a preset value, the lock-up clutch is operated (locked up) to eliminate transmission loss, thereby improving fuel consumption.
One example of such drive device having a hydraulic transmission with a lock-up clutch is a drive device having an engine power cut-off clutch disposed in a hydraulic transmission with a lock-up clutch (Japanese Patent Publication Application No. JP-A-2000-110916). In this drive device, a hydraulic pressure is supplied to each chamber provided between a cover of the hydraulic transmission and pistons of both clutches, and a pressure difference is generated between the chambers, whereby the engine power cut-off clutch and the lock-up clutch are operated.